import React, { Component } from 'react';

export default class Footer extends Component {

  // 全选checkbox的回调
  handleCheckAll = (event) => {
    this.props.checkAllTodo(event.target.checked)
  }

  // 清除已完成任务的回调
  handleClearAllDone = () => {
    this.props.clearAllDone()
  }

  render () {
    const { todos } = this.props
    // 已完成的个数
    const doneCount = todos.reduce((pre, todo) => pre + (todo.done ? 1 : 0), 0)

    // 总数
    const total = todos.length

    return (
      <div className="todo-footer">
				<label>
					<input type="checkbox" onChange={this.handleCheckAll} checked={doneCount === total && total !== 0 ? true : false}/>
				</label>
				<span>
					<span>已完成{doneCount}</span> / 全部{total}
				</span>
				<button onClick={this.handleClearAllDone} className="btn btn-danger">清除已完成任务</button>
			</div>
    )
  }
}